ALASKAN GLACIER STUDIES
Glacial Erosion. A sounding a little over a quarter mile from the terminus of Columbia. Glacier showed 600 feet of water, indicating clearly that the ice front is not afloat. It is, therefore, grinding actively upon the bottom of the fiord. Other soundings (Fig. 85) show clearly that it has not been afloat at any time when it extended farther south in Columbia Bay, the depths of water increasing gradually from 600 feet near the ice front
FIG. 35. SUBMABINH CONTOURS IN FRONT or COLUMBIA GLACIBR.
to 906 feet at a distance of 8£ miles and 1020 feet five miles from the ice front at the entrance to Prince William Sound, the slope being uniformly about 250 feet to the,mile. As the soundings, a half mile apart, show no interruptions in this even grade it is evident that there has been no significant basining of the fiord bottom. This would be normal in a straight section of fiord without constrictions of the side walls. In the narrower channel east of Heather Island the water is 57 feet deep a half mile south of the east ice